Misdiagnosis a Common, Often Hidden Problem

Until it happened to him, Itzhak Brook, a pediatric infectious disease specialist at Georgetown University School of Medicine, didn't think much about the problem of misdiagnosis.

That was before doctors at a Maryland hospital repeatedly told Brook his throat pain was the result of acid reflux, not cancer. The correct diagnosis was made by an astute resident who found the tumor? the size of a peach pit?using a simple procedure that the experienced head and neck surgeons who regularly examined Brook never tried. Because the cancer had grown undetected for seven months, Brook was forced to undergo surgery to remove his voice box, a procedure that has left him speaking in a whisper. He believes that might not have been necessary had the cancer been found earlier.

"I consider myself lucky to be alive," said Brook, now 72, of the 2006 ordeal, which he described at a recent international conference on diagnostic mistakes held in Baltimore. A physician for 40 years, Brook said he was "really shocked" by his misdiagnosis.

But patient safety experts say Brook's experience is far from rare. Diagnoses that are missed, incorrect or delayed are believed to affect 10 to 20% of cases, far exceeding drug errors and surgery on the wrong patient or body part, both of which have received considerably more attention.

Recent studies underscore the extent and potential impact of such errors. A 2009 report funded by the federal Agency for Healthcare Research and Quality found that 28% of 583 diagnostic mistakes reported anonymously by doctors were life-threatening or had resulted in death or permanent disability. A meta-analysis published last year in the journal BMJ Quality & Safety found fatal diagnostic errors in U.S. intensive care units appear to equal the 40,500 deaths that result each year from breast cancer. And a new study of 190 errors at a Veterans Affairs hospital system in Texas found that many errors involved common diseases such as pneumonia and urinary tract infections; 87% had the potential for "considerable to severe harm" including "inevitable death."

Misdiagnosis "happens all the time," said David Newman-Toker, who studies diagnostic errors and helped organize the recent international conference. "This is an enormous problem, the hidden part of the iceberg of medical errors that dwarfs" other kinds of mistakes, said Newman-Toker, an associate professor of neurology and otolaryngology at the Johns Hopkins School of Medicine. Studies repeatedly have found that diagnostic errors, which are more common in primary-care settings, typically result from flawed ways of thinking, sometimes coupled with negligence, and not because a disease is rare or exotic.

The problem is not new: In 1991, the Harvard Medical Practice Study found that misdiagnosis accounted for 14% of adverse events and that 75% of these errors involved negligence, such as a failure by doctors to follow up on test results.

Despite their prevalence and impact, such mistakes have been largely ignored, Newman-Toker and others say. They were mentioned only twice in the Institute of Medicine's landmark 1999 report on medical errors, an omission some patient safety experts attribute to difficulties measuring such mistakes, the lack of obvious solutions and generalized resistance to addressing the problem.

"You need data to start doing anything," said internist Mark L. Graber, founding president of the Society to Improve Diagnosis in Medicine and a leading errors researcher. Despite dozens of quality measures, Graber said, he is unaware of "a single hospital in this country trying to count diagnostic errors."

In the past few years, a confluence of factors has elevated the long-overlooked issue. In his 2007 bestseller, How Doctors Think, Boston hematologist-oncologist Jerome Groopman vividly deconstructed the flawed thought processes that underlie many diagnostic errors, including several he made during his long career.

More recently, an influential cadre of medical leaders has been pushing for greater attention to the problem. They cite concerns about the growing complexity of medicine and increasing fragmentation of the health-care system, as well as relentless time pressures squeezing doctors and the overuse of high-tech tests that have supplanted traditional hands-on skills of physical diagnosis.

"One of the reasons it's time to begin looking at it is that so many of the quality measures we use now assume that the diagnosis is the right one in the first place," said Christine Cassel. A member of the panel that wrote the 1999 Institute of Medicine report, she is now president and chief executive officer of the American Board of Internal Medicine.

But what if it's not?

In a much-cited essay, Robert Wachter, associate chair of the Department of Medicine at the University of California at San Francisco, wrote that a hospital could earn "performance incentives for giving all of its patients diagnosed with heart failure, pneumonia and heart attack the correct, evidence-based and prompt care?even if every one of the diagnoses was wrong."

Unlike drug errors and wrong-site surgery?mistakes that patient safety experts consider to be "low-hanging fruit" amenable to solutions such as color-coded labels and preoperative timeouts by the surgical team?there is no easy or obvious fix for diagnostic errors. Many are complex and multi-faceted, and may not be discovered for years, if ever, said Graber, a senior fellow at RTI International, a research firm based in Research Triangle Park, NC.

"There is probably nothing more cognitively complicated" than a diagnosis, he said, "and the fact that we get it right as often as we do is amazing."

But doctors often don't know when they've gotten it wrong. Some patients affected by misdiagnosis simply find a new doctor. Unless the mistake results in a lawsuit, the original physician is unlikely to learn that he or she blew it?particularly if the discovery is delayed. While diagnostic errors are a leading cause of malpractice litigation, the vast majority do not result in legal action.

Some environments are more susceptible to error than others. Graber calls the ER "a petri dish" for diagnostic mistakes: The doctor doesn't know the patient, the patient doesn't trust the doctor, and time pressures and frequent interruptions are the rule.

There is another reason such mistakes have been long ignored: They are regarded as an unusually personal failure in a profession where diagnostic acumen is considered the gold standard.

"Overconfidence in our abilities is a major part of the problem," said Graber, who believes doctors have gotten a pass for too long when it comes to diagnostic accuracy. "Physicians don't know how error-prone they are."

Many, he noted, wrongly believe that the problem is "the other guy" and that they don't make mistakes. A 2011 survey of more than 6,000 physicians found that 96% felt that diagnostic errors are preventable; nearly half said they encountered them at least once a month.

In the Texas Veterans Affairs study, more than 80% of cases lacked a differential diagnosis, in which a doctor not only declares what he or she believes is ailing the patient, but also lists other potential causes of the problem based on symptoms, test results and a physical exam.

"A differential helps people to cognitively focus," said Hardeep Singh, director of the Houston Veterans Affairs Patient Safety Center of Inquiry. Failure to ask "What else could this be?" can cause premature fixation on the incorrect diagnosis, said Singh, the study's lead author.

At Maine Medical Center, Robert Trowbridge, who directs the medicine clerkship program for Tufts University medical students, spearheaded a pilot program launched in 2010 to persuade doctors to anonymously report diagnostic errors, which would then undergo comprehensive analysis. He said he had to "hound" his colleagues to report mistakes. During the first six months, 36 errors that would otherwise have gone unreported were identified; most were deemed to have caused moderate to severe harm. Trowbridge said the program has changed how he practices.

"I'm much more reflective, much more attuned to the errors I'm prone to make. I work with checklists more."

The first-ever Canadian study of adverse events published in May 2004 in the Canadian Medical Association Journal found medical errors contribute to between 9,000 and 24,000 preventable deaths a year.

The study found an estimated 7.5% of patients?one out of 13-admitted to acute care hospitals in Canada in 2000 experienced one or more adverse events, considered an unintended injury or complication caused by health care management rather than by the patient's underlying disease. More than a third of those were judged to be highly preventable.

A report released shortly after by the Canadian Institute for Health Information noted almost a quarter of Canadian adults say they or a family member have experienced a preventable medical error, with drug errors and infections topping the list.

The institute's 2007 update reported that there has been progress, such as fewer objects left in after a procedure and more hospitals implementing patient safety strategies, many questions remain about the state of patient safety. And those questions aren't only how best to prevent harm. Little information is available about patient safety across the health-care continuum, and the rates and types of adverse events outside hospitals.

Surgical safety checklists are standard procedure in all Ontario hospitals since April 2010. The provincial mandate followed a study published in the New England Journal of Medicine the previous year that found complications and death from surgery are decreased with the use of a surgical checklist.